This invention lies in the field of apparatus for burning coal and is directed to such apparatus which is fed with fuel by a stoker conveyor and with air for combustion by a blower. It is more particularly directed to such an apparatus in which coal is fed upward and then radially outward over a burner grid and then outward over an ash ring. Although not so limited it is especially suitable for use in domestic type heating assemblies.
Stoker assemblies of this general type have been in use for many years and have taken many forms. Some units convey coal into a burner box with a generally flat grate at the bottom through which ashes fall naturally or by agitation. The green coal is deposited on top of the burning coal and the size of the fire is difficult to control within desired limits. The blanket of green coal confines the burning bed beneath it and many rather sizable clinkers are produced which are difficult to dislodge and remove.
In another type the burner box bottom is formed with a flat horizontal grate in one section and an ash tray in another. The coal is fed in at the margin of the grate and the entire mass is pushed across the box to discharge ashes at the far edge of the tray. Clinkers are formed as in the other type but they are dicharged without difficulty.
Both of the units mentioned operate reasonably well but they tend to produce rather incomplete combustion which is wasteful of energy and causes pollution. The larger clinkers particularly contain a substantial amount of unburned fuel.
The more complex forms of stokers frequently are constructed with a fire pot having a lower retort and an upper tuyere wall or burner head, with the stoker feeding coal into an opening in the bottom of the retort. The coal moves upward and burns primarily in the burner head, with the ash falling over the edge onto a grate or into an ash pit. Combustion is more complete but clinkers still form and fall into the ash pit with incomplete combustion. The burner head may be stationary or rotatable but the result is approximately the same. In some units a bracket is provided to engage large clinker formations extending beyond the burner head and separate them from the main body but they do not break down the clinkers themselves. This general type of apparatus, as commercially marketed, contains a very large number of parts and is unduly complicated, resulting in high construction and maintenance costs.